12. SequentialRangingReal

class SequentialRangingReal(name: str, instrument: Instrument, sigma: ArrayWUnits = None, gs_range_bias=None, state_definition=None, sequence_definition=None, epoch_sec=None, computed_measurements_dict=None)

Bases: Measurement

WORK-IN-PROGRESS

Attributes

computed_measurements_dict	DESC
epoch_sec	EpochArray in seconds of day
instrument	The instrument.
name	The name of the model.
sigma	The standard deviation of the measurement model.

Methods

compute_h_tilde_pos(relative_state, epoch_time)	This will generate the portion of h_tilde related to the position components.
compute_h_tilde_vel(relative_state, epoch_time)	This will generate the portion of h_tilde related to the position components.
compute_partials(target, epoch_array[, frame])	Stacks together measurement partials for an epoch array at different epochs.
computed_measurements(target[, epoch_array, ...])	This method compute the doppler measurement between target.name and self.instrument.name (2-way doppler).
generate_measurement_dataset(dataset_name, ...)	Generates a MeasurementDataSet object that can be used by filters downstream.
observed_measurements(file_name[, ...])	Reads measurements from a .json file.
partials(target, epoch, frame)
residuals(observed_meas, computed_meas)	Generates the measurement model's residuals given observed and computed ArrayWFrames.
write_observed_measurements(target[, ...])	Generates synthetic measurements and write them as a .json file.

compute_h_tilde_pos(relative_state: ArrayWUnits, epoch_time) → list

This will generate the portion of h_tilde related to the position components.

Parameters:

relative_state (ArrayWUnits) – relative state beween self and target

compute_h_tilde_vel(relative_state: ArrayWUnits, epoch_time) → list

This will generate the portion of h_tilde related to the position components.

Parameters:

relative_state (ArrayWUnits) – relative state beween self and target

compute_partials(target: ~scarabaeus.spacecraft.Spacecraft.Spacecraft, epoch_array: ~scarabaeus.timeAndFrame.EpochArray.EpochArray, frame: ~scarabaeus.timeAndFrame.Frame.Frame = J2000 (0 - SOLAR SYSTEM BARYCENTER)) → list

Stacks together measurement partials for an epoch array at different epochs.

Parameters:

• target (Spacecraft) – The target spacecraft.

• epoch_array (EpochArray) – The epochs.

• frame (Frame, optional) – The reference frame. Defaults to a J2000 Frame object.

Returns:

partials – A list with all the partials evaluated at different epochs in the epoch_array.

Return type:

list

computed_measurements(target: ~scarabaeus.spacecraft.Spacecraft.Spacecraft, epoch_array: ~scarabaeus.timeAndFrame.EpochArray.EpochArray = None, epoch_start: ~scarabaeus.timeAndFrame.EpochArray.EpochArray = None, epoch_end: ~scarabaeus.timeAndFrame.EpochArray.EpochArray = None, tstep: float = 1, frame: ~scarabaeus.timeAndFrame.Frame.Frame = J2000 (0 - SOLAR SYSTEM BARYCENTER), noisy: bool = False, prior_range_bias: float = None) → ArrayWFrame

This method compute the doppler measurement between target.name and self.instrument.name (2-way doppler). If a “receiver_station” is specified as an instrument (i.e. a ground station) 3-way dopller is computed instead.

Parameters:

• target (Body, Spacecraft) – target spacecraft as scb Spacecraft/Body object

• antenna_name (str) – name of the antenna to be used for Doppler

• epoch (Epoch) – epochs as scb Epoch object

• transmit_frequency (ArrayWUnits) – transmit frequency, used to compute the doppler count

• noisy (bool) – Noise flag, defaults to False

• receive_station (GroundStation) – receiving station object for three-way doppler, defaults to None

generate_measurement_dataset(dataset_name: str, measurement_type: str, target: ~scarabaeus.body.Body.Body, observed_meas: ~scarabaeus.timeAndFrame.ArrayWFrame.ArrayWFrame = None, frame: ~scarabaeus.timeAndFrame.Frame.Frame = J2000 (0 - SOLAR SYSTEM BARYCENTER), noisy: bool = False, prior_range_bias=None) → list[MeasurementDataSet]

Generates a MeasurementDataSet object that can be used by filters downstream.

Parameters:

• dataset_name (str) – The name of the MeasurementDataSet.

• target (Spacecraft) – The target spacecraft.

• epoch_list (EpochArray, optional) – The epochs. Defaults to None.

• epoch_start (EpochArray, optional) – The starting epoch. Defaults to None.

• epoch_end (EpochArray, optional) – The end epoch. Defaults to None.

• tstep (int, optional) – The integration timestep. Defaults to 1.

• observed_measurements (list, optional) – The observed measurements. Defaults to None.

• frame (Frame, optional) – The reference frame. Defaults to a J2000 Frame object.

• noisy (bool, optional) – Indicates if noise is added to the measurements or not. Defaults to False.

Returns:

mds_list – A list of MeasurementDataSet objects representing the measurements with their key properties to be used by a filter.

Return type:

list[MeasurementDataSet]

Notes

The MeasurementDataSet output is generated in 6 steps:

1. Computed measurements

2. Partials

3. Residuals

4. Sigmas

5. Pack everything in a list

6. Pack the list in a MeasurementDataSet object

observed_measurements(file_name, meas_name: str = 'meas_ideal', units: ~scarabaeus.units.Units.Units = unitless, frame: ~scarabaeus.timeAndFrame.Frame.Frame = J2000 (0 - SOLAR SYSTEM BARYCENTER)) → Tuple[EpochArray, ndarray, ArrayWFrame]

Reads measurements from a .json file.

Parameters:

• file_name (str) – The filename of the .json file containig the measurement information.

• meas_name (str, optional) – The name of the measurement data to access from the dictionary. Defaults to 'meas_ideal'.

• units (Units, optional) – Units to be used to write the output AWU. Defaults to unitless.

• frame (Frame, optional) – Frame to be used to write the output AWF. Defaults to a J2000 Frame object.

Returns:

meas_time_et, meas_sec, meas_obs – A tuple with the following values corresponding to their respective indices:

• [0] = meas_time_etEpochArray

  The time in ephemeris time.

• [1] = meas_Secnumpy.ndarray

  The times in seconds.

• [2] = meas_obsArrayWFrame

  An AWF with the quantities in AWU.

Return type:

Tuple[EpochArray, numpy.ndarray, ArrayWFrame]

Notes

The writing of the json assumes or requires units and frames.

partials(target: Spacecraft, epoch: EpochArray, frame: Frame) → list

residuals(observed_meas: ArrayWFrame, computed_meas: ArrayWFrame) → ArrayWFrame

Generates the measurement model’s residuals given observed and computed ArrayWFrames.

Parameters:

• observed_meas (ArrayWFrame) – The observed measurements values (O).

• computed_meas (ArrayWFrame) – The computed measurements values (C).

Returns:

residuals – AWF with the residual O-C.

Return type:

ArrayWFrame

write_observed_measurements(target: Spacecraft, epoch_array: EpochArray = None, epoch_start: EpochArray = None, epoch_end: EpochArray = None, tstep: float = 1, frame: Frame = None, noisy: bool = False, prior_range_bias: float = None, file_name: str = 'ideal_measurement') → None

Generates synthetic measurements and write them as a .json file. The input of this method encapsulate the ones needed for the “computed_meas” method in each measurement model class.

Parameters:

• target (Spacecraft) – The target spacecraft for which the range measurement is to be computed.

• epoch_array (EpochArray, optional) – An array of epochs (times) at which the range measurements should be computed. If provided, overrides epoch_start, epoch_end, and tstep.

• epoch_start (EpochArray, optional) – The starting epoch for the range measurement computations. Required if epoch_array is not provided.

• epoch_end (EpochArray, optional) – The ending epoch for the range measurement computations. Required if epoch_array is not provided.

• tstep (float, optional) – The time step, in seconds, between consecutive range measurements. If epoch_array is not provided. Defaults to 1 second.

• frame (Frame , optional) – The reference frame in which the range computation is performed. Defaults to None.

• noisy (bool , optional) – Whether to add noise to the computed range measurement. Defaults to False.

• prior_range_bias (float, optional) – A prior bias value to add to the computed range measurements. Defaults to None.

• file_name (str, optional) – The filename of the JSON in which the measurement is saved, Defaults to 'ideal_measurement'.

Return type:

None

ECLIPJ2000 = ECLIPJ2000 (0 - SOLAR SYSTEM BARYCENTER)

IAUEARTH = IAU_EARTH (399 - EARTH)

ITRF93 = ITRF93 (399 - EARTH)

J2000 = J2000 (0 - SOLAR SYSTEM BARYCENTER)

property computed_measurements_dict

DESC

property epoch_sec: EpochArray

EpochArray in seconds of day

property instrument: Instrument

The instrument.

property name: str

The name of the model.

property sigma: ArrayWUnits

The standard deviation of the measurement model.